The choline containing pneumococcal teichoic acids provide one of the systems of choice to probe into the functions and replication of these ubiquitous bacterial surface components. The key central conclusion that has emerged from our previous studies is that teichoic acids exert many of their physiological effects via control of the activity of cellular autolysins. The main problems of the new program are: (1) Purification of autolysin. (2) Controls of autolysin activity (on substrate level; by factors; on the level of enzyme assembly). (3) The nature of wall growth zone. (4) Biosynthetic experiments. (5) Role of autolysin in phage infection. During the first year of this program we have completed the purification of autolysin to homogeneity; it has been established that the pneumococcal Forssman antigen can combine in vitro with the pure autolysin and form a high molecular weight, inhibited complex. Biosynthetic experiments indicate that the Forssman antigen is not a precursor of wall teichoic acid. The essential role of bacterial (host) autolysin for the release of progeny phage particles has been established. BIBLIOGRAPHIC REFERENCES: Holtje, J.-V. and Tomasz, A.: Purification of pneumococcal N-acetylmuramyl-L-alanine amidase to biochemical homogeneity. J. Biol. Chem. 251: 4199, 1976.